SOLIDSTATECHEMISTRYVIAGLASSANDCERAMICS.ppt

Solid State Chemistryvia Glass and Ceramics John Tanaka and Edward J. Neth Chemistry Department University of Connecticut Storrs, Connecticut 06269 Glass, Ceramics and Mankind History Discovered in prehistory by unknown inventor Reconstructions of old civilizations Food and beverage storage Current technology Fiber Optics LC, electroluminescent, and plasma displays Chemistry Electric insulators Superconductors Electronic components Household goods Glass GLASS Quartz Coefficient of expansion 8 x 10?7 cm/cm/oC Softening point 1500oC 7740 Pyrex 80.5% SiO2 12.9% B2O3 3.8% Na2O 0.4% K2O 2.2% Al2O3 Coefficient of expansion 33 x 10?7 cm/cm/oC Softening point 820oC Working point 1200oC Container Glass 74.1% SiO2 1.8% Al2O3 8.8% CaO 1.4% MgO 13.0% Na2O 0.4% K2O Coefficient of expansion 92 x 10?7 cm/cm/oC Softening point 696 oC Working point 1000 oC Quartz STRUCTURES OF SiO2 Quartz, α and β (to 870oC) Tridymite ( 870oC to 1470oC) Cristobalite (1470oC to 1710oC) Beta quartz Tridymite, cristobalite Silicates SILICATE “ISLAND” STRUCTURES Orthosilicates Be2SiO4 phenacite (Mg, Fe)2SiO4 olivine ZrSiO4 zircon R3IIR2III(SiO4)3 garnet Pyrosilicates Sc2Si2O7 Si-O-Si = 180o Gd2Si2O7 Si-O-Si = 159o Nd2Si2O7 Si-O-Si = 133o Nets 1 connection dimer as above 2 connection chain or ring 3-connection 2 dimensional “infinite” structure or 3 dimensional “infinite” structure 4-connection 2 dimensional “infinite” structure or 3-dimensional “infinite” structure Representations To understand the structure of a three dimensional solid, more than one representation is needed It is not possible to display all structural elements using a single model Three Views 1. Classical Molecular view of P4O10 More Examples REPRESENTATIONS OF SOLID STATE STRUCTURES Ball and Stick P4O10 Picture NaCl Picture Zinc Blende Picture Polyhedral P4O10 Pi